1. Field of the Invention
The present invention relates to an improvement of a product bag unloading apparatus for unloading filled and sealed product bags from an intermittent transport type bag filling and packaging machine that fabricates such bags.
2. Description of the Related Art
As seen from Japanese Patent Application Publication (Kokoku) No. 63-57297 and Japanese Utility Model Registration No. 3,116,531, in a duplex-type intermittent transport type bag filling and packaging machine, two pairs of grippers that grip the right and left side edges of bags and suspend them with the mouth side up constitute a single group of grippers. Multiple groups of gripper pairs are provided at a constant pitch along a predetermined gripper traveling path, and the gripping surfaces of the two pairs of grippers belonging to the same group are provided in substantially the same plane when the respective bags are gripped. When each group of gripper pairs travels intermittently along the gripper traveling path, each one of the two pairs of grippers belonging to the same group is simultaneously supplied with a single bag (thus for a total of two (2) bags for one, same group of grippers). In the course of the subsequent packaging operations, each one of the bags gripped by the two pairs of grippers belonging to the same group is simultaneously subjected to successive packaging operations, such as opening the mouth of the bag, filling it with material to be packaged, sealing the mouth of the bag, etc. While the traveling path of the gripper pairs employed in Japanese Patent Application Publication (Kokoku) No. 63-57297 and Japanese Utility Model Registration No. 3,116,531 is circular, the traveling path can be linear or racetrack-shaped.
The advantage of a duplex-type intermittent transport type bag filling and packaging machine as described above in comparison with a simplex-type intermittent transport type bag filling and packaging machine (see Japanese Patent Application Laid-Open (Kokai) No. 61-33915, Japanese Patent Application Laid-Open (Kokai) No. 9-254931, and Japanese Patent No. 3,984,740) is its superior productivity as it can process two bags simultaneously.
When two product bags fabricated by a duplex-intermittent transport type bag filling and packaging machine are simultaneously discharged (or released by the gripper pairs) from the bag packaging machine, the bags are typically dropped onto a carry-out conveyor without getting further additional treatment and taken out of the machine in a double-row arrangement by the carry-out conveyor (Japanese Utility Model Registration No. 3,116,531).
However, subsequent treatment operations (such as sterilization, case packing, etc.) may sometimes require that the carry-out conveyor carry the bags out in a single row. For example, in Japanese Patent Application Publication (Kokoku) No. 63-57297, an intermediate conveyor, which is substantially perpendicular to the carry-out conveyor, is provided between the carry-out conveyor and the bag packaging machine; and by way of transferring product bags from the intermediate conveyor to the carry-out conveyor, the configuration used to transport product bags is converted from double-row transportation (on the intermediate conveyor) to single-row transportation (on the carry-out conveyor).
When an intermediate conveyor is employed as seen in Japanese Patent Application Publication (Kokoku) No. 63-57297, the orientation of the transported product bags is switched from the bag length direction (longitudinal direction) on the intermediate conveyor to the bag width direction on the carry-out conveyor. Accordingly, the problem with the method disclosed in Japanese Patent Application Publication (Kokoku) No. 63-57297 is that it cannot be used when the orientation of product bags conveyed in a single row must be in the length direction of the bags. In addition, another problem is that transferring (dropping) bags from the intermediate conveyor onto the carry-out conveyor shifts the orientation and position of the product bags and disturbs their alignment because of the vertical drop between the intermediate conveyor and the carry-out conveyor.
The applicant of the present application has developed and filed a patent application (Japanese Patent Application No. 2010-148099 which was filed in the U.S. with U.S. patent application Ser. No. 13/171,213) for a product bag unloading apparatus. In this product bag unloading apparatus, two product bags (arranged in a single row parallel to the bag width direction) simultaneously released from a duplex-type intermittent transport type bag filling and packaging machine are gripped by two (2) chucks, and the chucks in a single row in the thickness direction of the product bags are re-arranged during the process of being moved from a bag receiving position to a bag release position, and then the bags are released onto a carry-out conveyer. This product bag unloading apparatus makes it possible to release two product bags onto a carry-out conveyer such that the bags are aligned in a single row in the bags' lengthwise direction.
However, in product bag unloading apparatus of Japanese Patent Application No. 2010-148099 (Japanese Patent Application Laid-Open (Kokai) No. 2012-12041), two (2) product bags are gripped by two pairs of chucks, and when the chucks are moved from the bag receiving position to the bag release position, the chuck support frame supporting the two pairs of chucks at both ends swings and rotates within the horizontal; plane, as a result, the release position must be set at a position somewhat away from the bag receiving position so as to prevent interference from occurring between the product bags gripped by the chucks and the gripper pairs of the bag filling and packaging machine (see FIGS. 5 and 11 of this art) during the transferring operation. For this reason, the distance that the chucks are moved (and the distance that the product bags gripped by the chucks are transported) increases, and this creates problems in terms of improvement in productivity (increasing the rate of product bag unloading) and scaling down of the size of the entire packaging system including the product bag unloading apparatus. In addition, the construction of the product bag unloading apparatus of this art is complicated because of simultaneous transportation of two pairs of chucks gripping product bags from the bag receiving position to the bag release position.